An improved Newmark Method for predicting the whole-life performance of pile-reinforced slopes

In this paper a recently-developed Newmark-sliding block procedure, which can be applied to both unreinforced slopes, and slopes reinforced with a discretely-spaced row of vertical piles, is validated against dynamic centrifuge test data having a large number of sequential earthquakes causing a significant cumulative response. Five dynamic centrifuge tests conducted at 1:50 scale are reported here, two on unreinforced slopes with different input motion series’ and three on a pile-reinforced version of the same slope, all with normalized spacing of S/B = 4.7. The piled cases focus on reinforced concrete piles made with a new damageable scale model reinforced concrete, but also include an elastic pile case for comparison. The two input motion series consisted of four successive Chi-Chi (1999) motions and twelve successive Kobe (1995) earthquakes. It is shown that the Newmark method predicts permanent slope deformations well in all cases, and is therefore a promising tool for the analysis of the whole-life sesimic performance of slopes considering the cumulative effect of a number of strong earthquakes during the slope’s design life. Finally, it is also demonstrated that cumulative Arias intensity is an excellent index for correlating cumulative permanent slope slip across multiple sequential earthquakes for both reinforced and unreinforced cases